1. Field of the Invention
The present invention relates generally to a miniature bulb assembly adapted to be mounted on a base board. More particularly, the present invention relates to a miniature bulb assembly which assures that a plurality of miniature bulb assemblies can simultaneously be mounted on a printed base board during, e.g., a solder reflowing step in the same manner as resistors, capacitors or the like circuit components. Further, the present invention relates to a method of successively producing a number of miniature bulb assemblies of the foregoing type.
2. Description of the Related Art
FIG. 10 is a perspective view which shows by way of example a conventional miniature bulb assembly 100 adapted to be mounted on a base board 110, particularly illustrating a state before a socketless miniature bulb 102 is received in a bulb receiving hole in the form of a cylindrical cavity.
The miniature bulb assembly 100 includes a base portion 101 molded of synthetic resin in a cylindrical configuration, and the base portion 101 has a flange at the bottom part thereof. A pair of lead wires 102a extending from the miniature bulb 102 are inserted through lead wire holes 101b on a bottom wall 101a of the base portion 101 so that they are projected downward of the bottom wall 101a of the base portion 101 to serve as mounting terminals.
However, with the conventional miniature bulb assembly 100 as constructed in the above-described manner, since the lead wires 102a extending from the miniature bulb 102 serve also as terminals for mounting the miniature bulb assembly 100 on the base board 110, it has been found that there arise problems with the lead wires 102a. For example, in view of gastightness to be maintained during a sealing step, practical use of the lead wires 102a is restricted particularly in respect of dimensions and material to be employed therefor. Other problems are that the lead wires 102a have shortage in strength when they are used as mounting terminals and moreover they have a degraded property of soldering.
In recent years, there is a tendency that a solder reflowing process is usually employed for a step of automatically assembling circuit components on the base board 110. In addition, an excellent capability of provisionally mounting circuit components on the base board 110 has been required in conjunction with the assembling operation. However, as long as the lead wires 102a serve also as mounting terminals in the above-described manner, it is difficult to meet the requirement for assuring an excellent capability of firmly mounting circuit components. Therefore, there often occurs a malfunction that the miniature bulb 102 is undesirably floated up after completion of a soldering operation.
Since a pair of lead wire holes 101b determine a pitch for mounting the miniature bulb 102, an inner diameter of each lead wire hole 101b can not unavoidably be dimensioned to largely differ from an outer diameter of each lead wire 102a. Therefore, a high skillfulness is required for carrying out a step of allowing the lead wires 102a to be inserted through the lead wire holes 101b during an operation of assembling the miniature bulb 102 with the result that productivity is degraded.